Re: [PATCH RFC v3 09/12] hw/block/nvme: add verify command

[Klaus Jensen]

On Feb 16 15:12, Keith Busch wrote:
> On Mon, Feb 15, 2021 at 12:02:37AM +0100, Klaus Jensen wrote:
> > From: Gollu Appalanaidu <anaidu.gollu@samsung.com>
> > 
> > See NVM Express 1.4, section 6.14 ("Verify Command").
> > 
> > Signed-off-by: Gollu Appalanaidu <anaidu.gollu@samsung.com>
> > [k.jensen: rebased, refactored for e2e]
> > Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
> 
> Verify is a generic block command supported in other protocols beyond
> nvme. If we're going to support the command in nvme, I prefer the
> implementation had generic backing out of the qemu block API rather than
> emulate the entirety out of the nvme device.

You mean that the block API could provide a basic "check that we can
read this stuff without error"-call? Sounds reasonable enough, but since
the end-to-end data protection checks are performed in the device, we
need to pass the data buffers up anyway. If we had basic I/O (non-pi)
verify in the block API it would defeat the purpose if it provided those
buffers.

We've actually been asked directly on the availablity of Verify support
in QEMU, so I think this implementation as-is provides something useful
to users.

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